This invention relates generally to a wear adjuster of a disc brake, particularly to an air actuated a disc brake.
Disc brakes, as are well known, include a rotor and a brake caliper which straddles the rotor and can be actuated to apply a braking force to the rotor via opposed brake pads. In commercial vehicles, air actuation is almost universal, and an air actuator is provided at each vehicle wheel to actuate the brake caliper mechanically via a lever.
It is not generally practicable to arrange the actuating mechanism at an outboard side of the rotor, and thus the relevant components are always located at an inboard side. Particularly with vehicles having smaller wheels, such inboard mounting is rather space consuming so that design freedom of suspension and steering components may be compromised. Furthermore, the provision of additional features, such as wear sensors, may be problematic.
In one conventional design, the actuating mechanism includes an inboard tappet operable to directly apply an inboard brake pad, an automatic wear adjuster at one side of the tappet, a manual wear adjuster at the other side of the tappet, and a wear sensor having an electrical output indicative of brake pad and rotor wear. In addition to physically locating these components in the brake caliper, each component must also be sealed against moisture and dirt to avoid corrosion and/or seizure.
EP-A-1596092, in the name of the present applicant, proposes a rotary wear indicator mounted on a manual wear adjuster mechanism that has a visual output for giving an indication of pad wear to a mechanic. The wear indicator is removed for de-adjustment of the adjuster mechanism (for example, to replace worn brake pads) and must be re-set upon replacement.
What is required is a wear adjuster/wear indicator which is adapted for replacement or adjustment of brake pads without requiring re-setting or calibrating.